1. Field of the Invention
This invention relates to a sheet-sorting apparatus for sorting sheets discharged from a copy machine, printer or an image-processing device equipped with a function for finishing such stapling or the punching of holes.
2. Description of the Related Arts
We will explain sheet finishing apparatuses of the past that have accompanied image processing units to align a set of sheets and to staple them.
Sheet finishing apparatuses have a stacking tray for the final stacking of sheets having indicia formed thereupon and a processing tray established in the process to transport to the stacking tray. Sheets formed with images are stacked temporarily on a processing tray. Furthermore, sheets are aligned on this processing tray and then discharged to the stacking tray after having been stapled.
Next, we shall explain the aligning process on this processing tray according to FIG. 8. A movable aligning plate a and a fixed aligning plate f are mounted in opposition to each other on the processing tray. The movable aligning plate a is movable in the direction to narrow the gap of opposition with the fixed aligning plate f, in other words, it is movable in the direction which transverses that of the direction of sheet discharge.
Furthermore, in FIG. 8, the numbers of 1 to 7 indicate the procedures for aligning sheets. Numbers 1 to 3 are the procedures for aligning the nth sheet S (nxe2x88x921) and 4 to 7 are the final sheet S.
Sheet aligning is performed for each sheet, from the first sheet S to the nth sheet stacked on the processing tray. In other words, the movable aligning plate a starts at process 1 to strike the side edge of sheet S. This pushes the sheet S to the fixed aligning plate f, as shown in the procedure 2.
When the sheet S has been pushed against fixed aligning plate f, the movable aligning plate a returns to its original starting position again, as shown in procedure 3.
Then, another sheet S is led to the top of the prior sheet on the processing tray, and the movable aligning plate a again moves from its starting position to strike the side edge of the sheet S that has been newly led to the processing tray, to repeat the procedures of 1 to 3.
In this way, the repetitions of procedures 1 to 3 align the edges of the sheets while striking the edges of a plurality of sheets stacked on the processing tray.
Also, the movable aligning plate a aligns the nth and final sheet Sn using the procedures of 4 to 7 as shown in FIG. 8. In other words, when the final sheet Sn is led to the processing tray the movable aligning plate a starts the operation of procedure 4. In this way, the movable aligning plate a starts to strike the side edge of sheet Sn to push the sheet S against the fixed aligning plate f, as shown in procedure 5.
When the sheet Sn is pushed against the fixed aligning plate f, the movable aligning plate a returns to its starting position again, as shown in procedure 6, and again strikes the side edge of Sn as shown in procedure 7 to align the sheets.
The following are the reasons for striking the side edge of the final sheet Sn two times in repetition. Specifically, the aligning process for the sheets S other than the final sheet Sn is performed each time the sheet S is stacked on the processing tray. Therefore, all sheets are aligned a plurality of times for the number of times that sheets are stacked in repetition. The sheet edges will be correctly aligned the more times that this aligning process is repeated.
In respect to this, because the final sheet Sn is not stacked upon by any more sheets, the aligning process will only be performed once for that final sheet if the aligning process is not performed more than two times. However, there are cases in which it will not be done correctly if the aligning process is only performed one time. For that reason, in order to correctly align the sheets, including the final sheet Sn, the aligning process is performed specially for a second time.
Furthermore, on the apparatuses of the past, the distance of movement of the movable aligning plate a, in other words, from the starting position to the sheet striking position, had to be completely the same for sheets for the first sheet to the nth sheet and for the final sheet Sn.
In the same way as above, when aligning the nth sheet, the distance of movement for the movable aligning plate a, in other words, the distance from the starting position to the striking position, had to be completely the same for all sheets from the first sheet to the nth sheet. If the distance from the movable aligning plate a starting position to the sheet striking position is the same, so is the strength of the striking against the sheet the same.
However, when trying to align sheets, it is easier to align the sheets if there is some strength applied to the force of the strike. For example, if the sheet is greatly out of line, it is good to strike the sheet with some force. On the other hand if it is only slightly out of line, only a light force is required. The reason is that if you strike a sheet that is only slightly out of line with a great force, it will rebound from the fixed aligning plate f and become greatly out of line.
However, in apparatuses of the past, the force with which sheets have been struck has always been the same without any variation to the strength, thereby creating a situation in which sheet sets would not be correctly aligned.
An object of this invention is to provide a sheet finishing apparatus with a superior aligning process for better aligning of sheets.
Another object of the invention is to provide a sheet processing apparatus having a stacking tray for stacking sheets with indicia formed thereupon, a processing tray to receive the above described sheets in the process leading to this stacking tray. An aligning plate on the processing tray moves in the direction which transverses the direction of sheet discharge to align the sheets. After a stapling means staples the aligned sheets, the sheet set is discharged to the stacking tray.
Still another object of the invention is to combine a plurality of aligning actions when aligning the final sheet of a plurality of sheets in the same set wherein the distance from the aligning position of the aligning plate in the first aligning action to the starting position of the first aligning action is called L1 and the distance from the aligning position of the aligning plate in the final aligning action to the starting position of the final aligning action is called L2, the distances having the relationship of L1 greater than L2.
Another object of the present invention is for the final sheet to be the nth sheet wherein when aligning sheets from the first sheet to the nxe2x88x921 sheet, a first and a second aligning operation are performed wherein the distance from the aligning position in the second aligning operation to the aligning start position is L3, the relationships between these distances being L1 greater than L2 greater than L3.
The combination of the differences in strength of force of the striking of the edge of the sheets allows for an increase in the alignment of the sheets.
The processing time from the first sheet to the (nxe2x88x921) sheet is shorter, so it is possible to shorten the total processing time of the sheets formed with images.
Also, if the final sheet is fed to the processing tray, it is possible to expect better alignment of the leading set of sheets stacked even if the amount of offset is large.